Over-ear or circumaural headphones have been in use for many years. Over-ear headphones typically include a headband and a pair of earcups attached to opposing ends of the headband which completely encircle or surround a user's ears when worn. Over-ear headphones can include earcups of a closed-back or open-back design. Closed-back earcups have acoustically sealed or substantially-sealed backs. Open-back earcups have backs acoustically open to ambient environment and noise surrounding the earcups. While closed-back earcups have backs which are acoustically sealed to the ambient environment and noise, the earcups can include one or more vents configured to provide barometric pressure relief.
Over-ear headphones with closed-back earcups typically provide good sound isolation because they are sealed or substantially sealed off from ambient noise. However, they can also have certain disadvantages due to the closed design of the earcups. In some closed-back headphones, undesirable or unwanted resonances (e.g., modes) may develop inside a front volume of each respective earcup (e.g., air volume encapsulated inside the earcup or between the earcup and a wearer's skull and/or ear). Further, standing waves can accumulate in the earcups (e.g., between a driver housing plate of the earcup and a wearer's skull and/or ear) which can degrade sound quality considerably. Typically, these standing waves can occur in the 7-9 kHz range which can lead to undesirable or unwanted resonance in a frequency response of the headphones. As resonance frequency varies between wearers or users (e.g., due to anatomical differences), such unwanted standing wave resonance may be difficult to equalize with, for example, a digital signal processor (DSP) or graphic equalizer (EQ). As such, there remains a need for headphones with improved dampening features, and in particular, passive acoustic dampeners for closed-back, over-ear headphones.